1. Field of the Invention
This invention relates to a brake pressure control apparatus for a split braking system, and more particularly to a brake pressure control apparatus having two fluid pressure proportioning control valves for each of two braking fluid lines.
2. Description of the Prior Art
Conventionally, brake pressure control apparatuses have been proposed which include two fluid pressure proportioning control valves for a split braking system. Such fluid pressure proportioning control valves adapt so as to proportionally reduce increases in the output fluid pressure to increases in the magnitude of the input fluid pressure. In such prior brake pressure control apparatuses, one of proportioning control valves normally operate even when the other proportioning control valve fails to operate so that increases in the output fluid pressure relating to the one proportioning control valve still will be proportionally reduced. Thus sufficient braking fluid pressure will not be transmitted to the wheel cylinder.